Glass wiper blade for motor vehicles

ABSTRACT

A wiper blade ( 10 ) is proposed that serves to clean windows of motor vehicles. The wiper blade has an elongated, rubber-elastic wiper strip ( 14 ) which can be placed against the window to be wiped and is disposed substantially longitudinally axially parallel to one face, that is, the face oriented toward the window, of a striplike, spring-elastic support element ( 12 ), which is connected to a wiper arm ( 18 ) that is driven crosswise to the length of the wiper blade and can be urged toward the window. Even at high vehicle speeds, a requisite wiper blade contact pressure for attaining a swept field clean enough to meet legal requirements is achieved if the wiper blade ( 10 ) is provided with a leading-edge face ( 36  or  60 ), which extends longitudinally of the wiper blade and substantially parallel to the window and faces into the wind (arrow  38 ), and which crosswise to its length forms an acute angle with the window.

BACKGROUND OF THE INVENTION

The present invention relates to a wiper blade for windows of motorvehicles.

In wiper blades the support element is meant to assure the evenestpossible distribution of the wiper blade contact pressure on thewindows, over the entire swept field swept by the wiper blade. By meansof a suitable curvature of the unstressed support element—that is, whenthe wiper blade is not applied to the wiper blade—the ends of the wiperstrip, which in wiper blade operation is pressed entirely against thewindow, are urged toward the window by the then-stressed supportelement, even if the radii of curvature of spherically curved vehiclewindows differ in every position of the wiper blade. The curvature ofthe wiper blade must accordingly be somewhat greater than the greatestcurvature measured in the swept field of the window to be wiped. Thesupport element thus replaces the complicated support bracketconstruction, having two spring rails disposed in the wiper strip, ofthe kind employed in conventional wiper blades.

The invention takes as its point of departure a wiper blade of thistype. In a known wiper blade of this type (German Patent DE-PS 12 47161), the wiper blade, or its support element, which for reasons ofdistributing the contact pressure protrudes far past the wiper strip inthe middle region of the wiper blade, can on the one hand be engagedfrom below, on the front side facing into the wind, with an attendantbuildup of overpressure, by this overpressure. On the other hand, on theback side facing away from the wind, because of the structural formnoted above, a considerable negative pressure builds up. Although thewiper blade, which during operation usually executes a pendulum motion,constantly changes its position relative to the oncoming relative wind,even then one of its long sides is always more or less greatly exposedto the wind and is therefore called the front side, while its other longside is accordingly also thought of as the back side. At relatively highvehicle speeds, given the cooperation of these two aforementionedpressures, both of which are oriented counter to the wiper blade contactpressure, this contact pressure is reduced at least enough that properwiping is no longer possible. Increasing the wiper blade contactpressure against the window at high vehicle speeds could admittedlyreduce the severity of this problem, but at lower vehicle speeds, whenthe liftoff tendency is less, the friction between the wiper blade andthe window increases; this leads to undesirable noise buildup and toexcessively high stress on the drive components and on the rubber of thewiper.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a wiperblade which avoids the disadvantages of the prior art.

In keeping with these objects, one feature of present invention,resides, briefly stated, in a wiper blade provided with a leading-edgeface which extends longitudinally over the wiper blade and substantiallyparallel to the window and faces into the wind, and which crosswise toits length forms an acute angle with the window.

In the wiper blade of the invention, via the leading-edge face thatfaces into the wind, a force component aimed at the window is built up,which counteracts the liftoff tendency of the two pressures and thusassures excellent cleaning quality, at least in the region of the sweptfield swept by the wiper blade, that is, the region that is important tothe vehicle's driver. Depending on the size of the leading-edge faceand/or on the size of the approach angle α, this auxiliary contactpressure can be adapted to the variable demands that depend on the typeof vehicle. It is also advantageous in the arrangement of the inventionthat as a function of the vehicle speed, the contact pressure rises orfalls with this speed. Thus a suitably “high auxiliary contact pressure”is opposed only to the liftoff tendency that occurs at high speed.

A compact wiper strip is obtained if the leading-edge face is disposedon the face of the support element facing away from the window. Theauxiliary contact pressure is then distributed not in point form butareally, over the entire length of the wiper blade.

The embodiment of a leading-edge face can advantageously by attained inthat it is embodied on a separate, elongated component that is solidlyjoined to the support element.

A simple structure of such a separate component is obtained in that,seen in cross section, it has at least approximately the shape of atriangle, one side of which contacts the face of the support elementfacing away from the window, and also that the leading-edge face isembodied on another side of the triangle. In certain cases, it can beadvantageous to equip the leading-edge face at least partially with ahollow curvature facing into the wind.

Securing the component to the one side of the support element isachieved economically by a glued connection. So that the distribution ofthe contact pressure effected by the support element will not beimpaired, the component is made from a rubber-elastic material whosehardness is no greater, and is preferably less, than the hardness of therubber-elastic wiper strip. Advantages in terms of production areattained if the component is made from a suitable plastic.

The length, and the width and height projected in the operatingdirection of the wiper blade, of the leading-edge face is designed tosuit the requirements. In certain cases it is expedient if theleading-edge face extends at least nearly over the entire length of thewiper blade.

Further advantageous refinements and features of the invention arerecited in the ensuing description of an exemplary embodiment shown inthe accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 shows a side view of a wiper blade of the invention;

FIG. 2 shows a plan view on the wiper blade of FIG. 1;

FIG. 3 shows a section through the wiper blade, taken along the lineIII—III in FIG. 1 and shown on a larger scale in schematic form; and

FIG. 4 shows a basic illustration of the wiper blade of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A wiper blade 10 shown in FIGS. 1 and 2 has a single- or multi-part,elongated, spring-elastic support element 12, to whose underside anelongated, rubber-elastic wiper strip 15 is secured longitudinallyaxially parallel to it. A connection device 16 is disposed on the topside of the support element, and with its aid the wiper blade 10 can bedetachably connected to a driven wiper arm 18. A hook acting as acounterpart connection means is formed onto the free end 20 of the wiperarm 18 and grasps a pivot pin 22 that belongs to the connection device22 of the wiper blade. The securing between the wiper arm 18 and thewiper blade 10 is taken on by securing means not shown in further detailbut known per se and embodied as adapters. The wiper arm 18 and thusalso the hook on the end 20 of the arm is urged in the direction of thearrow 24 toward the window to be wiped, whose surface to be wiped issuggested in FIG. 1 by a dot-dash line 26. Since the dot-dash line 26 ismeant to represent the greatest curvature of the window surfaces, it isquite apparent that the curvature of the wiper blade 10, which restswith its two ends on the window, is greater than the maximum curvatureof the window. Under the contact pressure (arrow 24), the wiper bladepresses with its wiper lip 28 over its entire length against the windowsurface 26. This causes a tension to build up in the bandlike,spring-elastic support element 12, and this tension assures a propercontact of the wiper strip 14 or wiper lip 28, over their entire length,with the motor vehicle window.

The particular design of the wiper blade 10 will be described in furtherdetail, especially in terms of FIGS. 3 and 4. On the upper face 30 ofthe bandlike support element 12, facing away from the windshield 25, asingle- or multiple-part component 32 extending longitudinally of thewiper blade 10 is secured; it is made from a rubber-elastic material,preferably a plastic, whose hardness is less than the hardness of therubber-elastic wiper strip 14. This wiper strip 14 is disposed on thelower face 34, toward the window 25, of the support element 12. As FIG.1 shows, the component 32 extends over the entire length of the wiperblade 10. It has a cross section in the shape of a triangle or wedge(FIG. 3). In the exemplary embodiment, to that end, the shape of anon-isosceles triangle has been selected. The longest side 36 of thistriangle forms a leading-edge face for the relative wind created by themotor vehicle, which is symbolized by the arrow 38 in FIG. 3. A second,shorter side 40 of the triangular shape faces toward the upper face 30of the support element 12. The two faces, facing one another, of thesupport element 12 and 40 of the component 32 are joined together bygluing.

To explain the mode of operation of the wiper blade of the invention,see FIG. 4, in which all the necessary parts of the wiper blade areshown in basic form. During operation of the wiper blade, whoseoperating motion is represented by the double arrow 42 when the wiperblade is displaced with its wiper strip 14 over the surface 26 of thewindow, the support element 12 is located in a plane that extendssubstantially parallel to the surface 26 of the window. The wiper blade10 then experiences a contact pressure 52 (FIG. 3) that is counteredduring wiper blade operation, especially at high vehicle speeds, by aliftoff tendency acting in the direction of the arrow 54 in FIG. 4.Since the leading-edge face 36 of the component 30 facing into the wind38, and forms an acute angle a with the surface 26 of window 25, thepressure of the relative wind 38 generates a force component that isrepresented in FIG. 4 by the arrow 56. This force component 56 actscounter to the liftoff tendency (arrow 54) in FIG. 3 and thus keeps thecontact pressure (arrow 52) within the legally prescribed range. In adeparture from the exactly triangular cross-sectional shape shown inFIG. 3 for the component 12, this component can also be embodied suchthat its side facing into the wind 38 is provided with a hollowcurvature 60, which is represented in FIG. 4 by a dot-dash line. Buteven with the provision of a hollow curvature on the side toward thewind 38, the component 30 maintains its basically triangularcross-sectional shape and thus also the possibility of the developmentof a force component (arrow 56 in FIG. 4) from the contact pressure withwhich the wind (arrow 38) meets the curved leading-edge face 60.

What is claimed is:
 1. A wiper blade for windows of motor vehicles, comprising a curved, band-shaped, spring-elastic support element which distributes a pressure applied by a wiper arm and has a concave and a convex surface which defines corresponding planes; an elongated rubber-elastic wiper strip placeable on a window to be wiped and mounted to said concave surface of said support element which faces the window, substantially longitudinally parallel to said concave surface; a connection device provided for a wiper arm and arranged directly on a convex side of said support element; and a component which is separate from said wiper strip and is mounted directly to the convex surface of said support element so as to form a leading-edge face extending in a longitudinal direction of the support element and forming, as seen crosswise to its longitudinal extension, an acute angle with a plane which extends parallel to a plane formed by said convex surface.
 2. A wiper blade as defined in claim 1, wherein said leading-edge face is disposed on a face of said support element which faces away from the window.
 3. A wiper blade as defined in claim 1, wherein said leading-edge face is formed as a separate elongated component which is solidly joined to said support element.
 4. A wiper device as defined in claim 3, wherein said component, seen in a transverse cross-section, has at least approximately a shape of a triangle with one side contacting a face of said support element facing away from the window, and said leading-edge face being formed on another side of said triangle.
 5. A wiper device as defined in claim 3, wherein said component is glued to the one side of said support element.
 6. A wiper device as defined in claim 3, wherein said component is composed of a rubber-elastic material with a hardness which is no greater than a hardness of said rubber-elastic wiper strip.
 7. A wiper device as defined in claim 3, wherein said component is composed of plastic.
 8. A wiper blade as defined in claim 1, wherein said leading-edge face extends at least nearly over an entire length of the wiper blade. 